Development Of A Phase Change Temperature Regulating Fire-Fighting Suit Lining Based On The Characteristics Of Human Body Heat Production In Warm And Humid Environment

Firefighters are in a state of high labor intensity during fire rescue,and the heat production and perspiration of the human body are at a high level.The accumulation of this part of heat and humidity in firefighting suits will cause discomfort to personnel,and even cause firefighters to appear in severe cases.Heat stress symptoms,life-threatening.The current fire suits are mainly in the form of multi-layer fabrics to enhance the thermal insulation performance,and the heat and moisture produced by the human body cannot be discharged.In addition,the high temperature of the fire will cause falling objects in the building,but the current fabric structure of fire clothing does not have the ability to resist the impact of falling objects in the fire,which brings great hidden dangers to firefighters in the process of rescue tasks.Therefore,adding tempering and buffering functions on the basis of current fire suits is a promising new direction.Based on this,this paper studies the inner lining of firefighting suits with both tempering and buffering functions,and the research results are as follows:(1)The experiment was carried out using the artificial environment experimental cabin system to obtain the heat production law of the human torso under the high temperature and high humidity environment:it was found that the overall trend of human skin temperature increased with time in both the working conditions of wearing fire fighting suits and not wearing fire fighting suits.While rising,there is a fluctuating section of the skin temperature curve of the people who do not wear fire suits,that is,the skin temperature has a falling stage during the exercise process,and the heat production ranking of each area of the torso is obtained.(2)Sodium sulfate decahydrate was selected as the phase change cooling material,potassium carbonate,boric acid and xanthan gum were added to improve the supercooling phenomenon of the material,and a phase change cooling material that met the requirements of fire protection was prepared.The microscopic analysis,melting-solidification test and DSC test of the prepared phase change material show that the best performance is obtained when the ratio of sodium sulfate decahydrate and potassium carbonate is 3:1.At this time,there is no phase separation in the whole system before and after the phase change of the material.,the mixture has no precipitation in the molten state,no bubbles after condensation,and the solid material after crystallization is uniform and free of impurity precipitation.(3)A fire-fighting suit lining with a bladder structure with buffering function was designed,and the bladder material was prepared with vinyl-terminated polydimethylsiloxane,silica and other materials,and the bladder material with the best performance was obtained through mechanical testing.Under this ratio,the elastic modulus of the bladder material is331.8k Pa,the elongation at break is 285.64%,and the tensile strength and other mechanics are 1.045MPa.The microscopic morphology observation showed that the capsule material formed colloidal particles after curing reaction,which could enhance the wear resistance of the capsule material.The optimal filling pressure of the bag material was deduced by the ideal gas state equation and the spring model,and the actual value of the optimal filling pressure of the bag was 1.11×10~5Pa through the verification test.(4)After filling the phase change material into the bag for sealing,the finished lining was obtained,and the mechanical test and cooling characteristic test were carried out on it.It was found that the lining had stronger energy absorption characteristics at a lower strain rate.-The Rivlin hyperelastic model has high accuracy in predicting the mechanical response of the bladder structure;the average temperature of the human skin is significantly lower than that of the ordinary fire suit with a phase change cooling lining,and the maximum temperature difference between the two is 3℃,indicating that the lining can improve the thermal comfort of personnel to a certain extent.